PRETORIA — A subdued Oscar Pistorius on Tuesday described dinner at home, chatting and looking at cellphone photos with Reeva Steenkamp on the last night of her life. Then he erupted in anguished howls and heaving sobs while testifying at his murder trial about the moments when he says he realized he had shot his girlfriend through a closed bathroom door.

The shocking spectacle of what appeared to be a tormented man highlighted the drama of Pistorius’s inspirational rise and sudden fall. The South African double-amputee runner captured the world’s attention when he successfully fought for permission to run in the 2012 Olympics on his carbon-fiber prostheses. The very next year, he was facing charges for killing the woman he said he loved.

The court in Pretoria, the South African capital, adjourned because of the star athlete’s breakdown, ending a day on which Pistorius spoke of the loving aspects of his relationship with Steenkamp in testimony designed to counter a prosecution picture of him as temperamental and overbearing, and then outlined his version of the final hours before the shooting.

‘‘I sat over Reeva and I cried,’’ said Pistorius, telling how he broke open the door in his bathroom in the early hours of Feb. 14, 2013, to discover his bloodied girlfriend slumped in the cubicle. ‘‘I don’t know how long I was there for.’’

Pistorius has said in statements that he shot Steenkamp after mistaking her for an intruder in his bathroom. Tuesday marked the first time he has spoken publicly about the details of the fatal shooting. Prosecutors call Pistorius’s story an intricate lie and maintain he intentionally killed his 29-year-old girlfriend, a model and reality TV show star, after an argument.

The 27-year-old Olympian faces a life sentence with a minimum of 25 years before parole if convicted of premeditated murder. The judge, Thokozile Masipa, will deliver the verdict because South Africa does not have a jury system.

Pistorius didn’t stand up when the judge left, and also started to wail as he slumped in his seat.

When Masipa returned, she ended proceedings for the day. Pistorius had by that time come back, jaw clenched, to the witness box. He was composed when he left the court and walked to a waiting vehicle. The trial was to reconvene on Wednesday.

Led by defense lawyer Barry Roux for the second day of his testimony, the runner provided more detail about his timeline of events leading up to the shooting. He said the couple had dinner about 7 p.m. and later sat chatting in the bedroom with the television on, and that Steenkamp showed him some photographs on her phone. He said he fell asleep between 9 and 10 p.m. and woke up early the next morning.

At that point, he said, Steenkamp asked him, ‘‘Can’t you sleep?’’

“ ‘No, I can’t,’ ’’ Pistorius said he replied. Then, he said, he stepped out to the balcony to get fans, and when he returned to the darkened bedroom he heard a noise from the bathroom.

‘‘That’s the moment that everything changed,’’ Pistorius testified.

Pistorius said he felt fearful and vulnerable as he moved to the bathroom, walking only on his stumps because he had removed his prosthetic legs before going to bed. He said he was screaming for Steenkamp to call the police.

‘‘I wasn’t sure if someone was going to come out the toilet and attack me,’’ he said.

He also testified he heard a door slam, which he said he took as ‘‘confirmation’’ that there was an intruder in the bathroom, and fired four shots at the toilet cubicle with his 9mm pistol.

After the shots, Pistorius said, he searched for Steenkamp in his bedroom, patting the bed where he says he thought she was in the dark, searching on the floor next to it where he thought she might be hiding, and also behind the curtains.

‘‘It was at that point . . . that it first dawned on me that maybe it was Reeva in the toilet,’’ Pistorius said.

He said he screamed for help.

In earlier testimony Tuesday, Pistorius denied three other charges against him relating to firing a gun in public on two occasions, and illegal possession of ammunition.

He said he wasn’t to blame for a shot going off in a busy Johannesburg restaurant because a friend handed him an ‘‘unsafe’’ gun with a bullet in the chamber under the table. He also said he wasn’t guilty of illegally possessing .38-caliber ammunition in his home because he was safekeeping it for his father and had no intention to use it.

In a dramatic scene before the packed courtroom Tuesday, Pistorius left briefly at one point to change out of his dark suit and into a white shirt and shorts, similar to the clothes he was wearing when he killed Steenkamp.

Prompted by his lawyer, Pistorius then took off his prosthesis and stood on his stumps by the bullet-marked toilet door, which has remained in the courtroom for much of the trial. It appeared to be an effort by the defense to illustrate what they describe as the Olympian’s vulnerability at the time of the shooting.

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